Simplex liquid handling apparatus hav-
ing improved electrode type control
system



y 1966 R. MANDELBAUM ETAL 26,033

SIMPLEX LIQUID HANDLING APPARATUS HAVING IMPROVED ELECTRODE TYPE CONTROLSYSTEM Ongmal Flled Oct 16 1961 INVENTORS. Poker? mande/baum BY Frank 6.Weis arm/ma? United States Patent 26,033 SIMPLEX LIQUID HANDLINGAPPARATUS HAV- ING IMPROVED ELECTRODE TYPE CONTROL SYSTEM RobertMandelhaum and Frank G. Weis, both of Kansas City, Mo., assignors toUnion Tank Car Company, Chicago, Ill., a corporation of New JerseyOriginal No. 3,155,048, dated Nov. 3, 1964, Ser. No.

145,343, Oct. 16, 1961. Application for reissue Oct. 8,

1965, Ser. No. 496,249

Claims. (Cl. 103-241) Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; rnatterprinted in italics indicates the additions made by reissue.

[The] This invention relates to material handling apparatus, and moreparticularly, to apparatus for receiving material until a predeterminedamount has accumulated, at which time the material is automaticallyejected by force. Apparatus of this type has particularly usefulapplication in installations where material such as sewage or the likemust be discharged against forces such as gravity.

It is well known to control the operation of apparatus of this naturewith electrical control systems. Such systems are conventionallyactuated by the completion of an electrical circuit by virtue ofphysical contact established between an electrode and the material whenthe latter reaches a predetermined accumulation in the retaining vessel.Once activated, the control system initiates a cycle during which thematerial is ejected from the vessel. Ideally, then, the apparatus isreturned to its material-receiving condition until subsequentaccumulation establishes contact with the electrode.

Heretofore, one disadvantage with such systems has been that theejection cycle is initiated whenever such contact is established andcontinues substantially without interruption until the contact isbroken. If, as often occurs, material clings to the electrode andestablishes contact to ground by touching a wall of the vessel or thelike, the apparatus continues in the ejection cycle. This results inloss of use of the apparatus and waste of the ejecting vehicle (oftencompressed air) until the necessary maintenance of the electrode isperformed.

When automatic means is incorporated into the system to shut off theair, conventional systems have heretofore had no means for automaticallyejecting the accumulated material.

Accordingly, it is the most important object of this invention toprovide apparatus having an electrical control system which restores theapparatus to its materialreceiving condition for a predetermined periodof time following the ejection cycle, thereby obviating the difficultycaused by fouling of the material sensing electrode.

Another important object of our instant invention, and in conjunctionwith the foregoing object, is to provide apparatus for handling materialthat is not solely dependent upon the material sensing device forreturning the apparatus to its material-ejecting condition.

Yet another object of our invention is the provision of time delaycomponents to insure that the apparatus remains in thematerial-receiving condition for a predetermined length of timefollowing the ejection cycle to permit the desired accumulation ofmaterial before ejection thereof.

A still further object of this invention is to provide material-handlingapparatus which is substantially maintenance-frec, thereby permittinguse of the apparatus in relatively inaccessible places such asunderground sewage installations or the like.

Still another object of our invention is the provision of such apparatushaving an electrical control adapted for utilization of commerciallyavailable alternating cur- Re. 26,033 Reissued May 24, 1966 See rentelectrical energy, yet having direct current circuits therein to permitgreater sensitivity of the material sensing device and longer life ofthe sensing electrodes.

The drawing is a schematic diagram of an electrical control formaterial-handling apparatus [emboding] embodying the principles of theinstant invention with the materiahreceiving vessel shown in crosssection.

The material-handling apparatus includes a materialreceiving vessel 10which is normally closed, and has an inlet pipe 12 communicatingtherewith and adapted to be coupled with a source of material to behandled. Pipe 12 is provided with a check valve 14 therein to permit theflow of fluid in the direction of vessel 10 and to prevent flow in theopposite direction. An outlet pipe 16 also communicates with vessel 10and is pro vided with a check valve 18 for permitting the flow of fluidin only one direction through outlet 16. It will be understood thatoutlet 16 is adapted to lead to a suitable place of discharge for thematerial to be handled by the apparatus.

In order to facilitate the accumulation of material within vessel 10,the latter is provided with a pipe 20 communicating therewith and havinga 3-way valve 22 therein. A vent pipe 24 extends from valve 22 for thepurpose of placing vessel 10 in communication with the atmosphere whenvalve 22 is disposed in its normal position. A conduit 26 is also incommunication with valve 22 and is adapted to be coupled to a source ofpressurized fluid such as compressed air or the like, for conductingsuch pressurized fluid into vessel 10 when valve 22 is shifted to itsalternate position. The pressurize-d fluid is utilized for the purposeof ejecting the material from vessel 10.

An electrical control is provided for the apparatus and includes meansfor sensing the level of material within vessel 10 in the form of anelectrode 28, preferably extending into vessel 10 adjacent the topthereof and in position to be engaged by the material when the latterhas reached a predetermined accumulation within the vessel. In additionto electrode 28, the electrical control for the material-handlingapparatus includes a source of electrical energy shown as contacts 30and 32, an electrically responsive switching device 34, a timer 36, asolenoid 38, a time delay switching element 40, a rectifier 42, and acapacitor 44.

The electrically responsive switching device 34 includes a coil 46, anormally open, single-pole, single-throw switch 48 having a movable pole50, and a fixed contact 52. Device 34 also includes a second normallyopen, single-pole, single-throw switch 54 having a movable pole 56 and afixed contact 58. The poles 56 and of device 34 are operably coupledwith coil 46 to be shifted into engagement with respective contacts 58and 52 upon en ergization of the coil 46.

Timer 36 may be of any conventional type and includes an electricallyoperated time delay mechanism 60 operably coupled with a single-pole,double-throw switch 62. The latter has a movable pole 64, a normallyclosed fixed contact 66, and a normally open fixed contact 68.Additionally, mechanism 60 is operably coupled with a normally closed,single-pole, single-throw switch having a movable pole 72 and a fixedcontact 74.

Switching element 40 includes a component 76 operably coupled with anormally closed, single-pole [singepole], single-throw switch 78 havinga movable pole 80 and a fixed contact 82. Component 76 is operablycoupled with pole 80 to effect opening of switch 78 upon energization ofcomponent 76 and may be a thermoelectric heating element adapted to openswitch 78 upon the passage of current through component 76. [Elment]Element 40 includes the characteristic of maintaining switch 78 in itsopen condition for a predetermined period of time, thus, thethermoelectric component 76 is ideally suited for element 40.

Rectifier 42 may be of any suitable type capable of convertingalternating current electricity into direct current for a purpose to beexplained later. Capacitor 44 may also be of any suitable type and therating thereof is preferably calculated for cooperating with therectifier for providing direct current energy, as will be explained morefully as the specification progresses.

The normally open fixed contact of switch 48 is electrically coupledwith contact 30 of the source of electrical energy by line 84. The othercontact 32 of the source is electrically coupled with one side of timermechanism 60 by a line 86. Line 86 is connected to one side of component76 by line 88, and one side of solenoid 38 is connected with line 88 byline 90. The other side of solenoid 38 is connected with the fixedcontact 66 of switch 62 by line 92. The fixed contact 68 of switch 62 iselectrically coupled with the other side of component 76 by line 94.Lead 96 connects the fixed contact 74 of switch 70 with line 86, and themovable pole 72 of switch 70 is coupled with the movable pole 56 ofswitch 54 with line 98. A line 100 interconnects the movable pole 64 ofswitch 62, and the movable pole 50 of switch 48, while the other side ofmechanism 60 is connected to line 100 by a line 102.

lead 104 connects the movable pole 80 of switch 78 to line 84, while thefixed contact 82 of switch 78 is coupled. to rectifier 42 by line 106.The other side of rectifier 42 is coupled with the coil 46 of device 34by line 108. Line 110 interconnects one side of capacitor 44 with line108. and the other side of capacitor 44 is connected to electrode 28 byline 112. The latter is connected to the opposite side of coil 46 by aline 114. A line 116 couples line 114 to the fixed contact 58 of switch54.

in operation, valve 22 is normally in position to vent the inside ofvessel to the atmosphere and to facilitate the flowing of materialtherein through inlet 12. When the material has accumulated in vessel 10to a level wherein the material contacts electrode 28, a circuit iscompleted which energizes coil 46 of device 34. This energizing circuitmay be traced from contact 30, through line 84, lead 104, pole 80 andcontact 82 of switch 78, line 106, rectifier 42 (which converts theelectricity into direct current), line 108, coil 46, line 114, line 112,electrode 23 to ground through the material and vessel 10. Upon beingenergized, coil 46 operates switches 54 and 48. The closing of switch 48completes a circuit to energize solenoid 38 traceable from contact 30,through line 84, contact 52 and pole 50 of switch 48, line 100, pole 64and contact 66 of switch 62, line 92, solenoid 38, line i 90, line 88,line 86, to contact 32.

Solenoid 38 is thus energized and is operably coupled with valve 22 toefiect shifting of the latter to its alternate position. This terminatesthe communication of vessel 10 with the atmosphere and permitpressurized fluid from i the source to pass through conduit 26, pipe andinto vessel 10 where it forces the accumulation of material thereinoutwardly past check valve 18 through outlet 16. At the time solenoid 38is energized, the closing of switch 48 also energizes mechanism 60 oftimer 36. Th circuit energizing timer 36 may be traced from contact 30,through line 84, switch 48, line 100, line 102, mechanism 60, line 86 tocontact 32. Thus, mechanism 60 is energized to effect operation of thetimer switches after a predetermined delay of time which may be preset,depending upon the requirements for the apparatus.

At the time coil 46 of switching device 34 is energized, a holdingcircuit is closed to continue the energizing of coil 46 for apredetermined length of time. This holding circuit may be traced fromcontact of the electrical source, through line 84, lead 104, switch 78,line 106, rectifier 42, line 108, coil 46, line 114, line 116, switch54, line 98, switch 70, lead 96, line 86 to contact 32. Thus when thematerial is ejected from within vessel 10 to a level where there is nolonger physical contact between the material and electrode 28, and theinitial circuit energizing coil 46 previously described is broken, theholding circuit just enumerated maintains the energy to coil 46.Throughout this time, valve 22 is held in its alternate position and thematerial is continuously ejected from within vessel 10.

After mechanism 60 of timer 36 has been energized for a predeterminedlength of time, the mechanism shifts the poles 64 and 72 of switches 62and 70 respectively. Pole 64 shifts into contact with normally opencontact 68 of switch 62 and away from the normally closed contact 66thereof. This breaks the energizing circuit to solenoid 38, allowingvalve 22 to return to its normal position venting vessel 10. Up untilthis time the valve circuit has not been broken, so if solenoid 38 iscontinuously energized the valve 22 continues to admit and wastepressurized fluid, not allowing the vessel 10 to fill. The shifting ofpole 72 from normally closed contact 74 of switch 70 breaks the holdingcircuit previously described and thereby permits de-encrgization of coil46. When coil 46 is deenergized, the movable poles 56 and of switches 54and 48, respectively, shift to their normally open positlons.

As timer 36 shifts the switches thereof, a circuit may be traced fromcontact 32 of the source through line 86, line 88, component 76 ofelement 40, line 94, contact 68 and pole 64 of switch 62 line 100,through pole 50 and contact 52 of switch 48 if the latter is closed,through line 84 to contact 30 of the source. However, as has beenpointed out, the shifting of switch 70 by timer 36 should break theholding circuit and tie-energize coil 46, thereby permitting switch 48to open and prevent the circuit that would energize component 76 ofelement 40 from being closed. On the other hand, if for some reason,such as the maintaining of electrical contact between electrode 28 andground, through the walls of vessel 10 by material clinging to electrode28 and touching the walls or the like, coil 46 will remain energizedthrough its primary energizing circuit previously described. Thus, thebreaking of the holding circuit will be not release switches 54 and 48and the circuit energizing component 76 will be made with pole 50engaging contact 52 of switch 48. When this occurs, the switching device34 remains operated and switches 54 and 48 are in their closedpositions, the mechanism of timer 36 remains energized, the switches 62and remain in their shifted positions through the action of mechanism60, solenoid 38 is de-energized and valve 22 returns to its normalposition. Thus, if nothing is done to prevent this situation, theapparatus remains in the filling cycle and can never eject its contents.This condition has, in the past, caused a great deal of difiiculty inheretofore known material handling devices.

To obviate this undesirable condition, safety means is incorporated intothe control for the apparatus. Such safety means includes the energizingcircuit for component 76 previously described. It may be readily seenthat when switch 62 of timer 36 is simultaneously closed with switch 48of switching device 34, component 76 is directly connected to the sourceof electrical energy. This causes a heating of component 76, resultingin the opening of switch 78 of element 40 after a predetermined delay toallow the vessel 10 to fill. When electrical contact is broken betweenpole 80 and contact 82 of switch 78, the primary energizing circuit forcoil 46 of device 34 is broken. This permits switches 54 and 48 to opento break the energizing circuit for timer 60 and relay 40, irrespectiveof whether or not electrode 28 has become fouled and continues to sensethe necessary accumulation of material within vessel 10 to initiate theejection cycle.

It may be readily seen that as soon as switch 78 again closes, coil 46will re-energize, permitting the closing of switches 54 and 48, andcausing the apparatus to reinitiate the ejection cycle. Thus it isimportant that element 40 allow switch 78 to remain closed long enoughto permit vessel 10 to fill with a substantial amount of material beforecoil 46 is de-energized. Preferably, element 40 is adjustable and may beselectively set to leave switch 78 closed for the desired period oftime. Normally an element with delay ability of from to minutes issatisfactory with a delay setting of thirty seconds being desirable formany material handling installations. Additionally, it is necessary thatswitch 40 have a remake time of sufficient length to allow relaycontacts 48 and 54 and timer mechanism 60 to reset. Thus, once open, theswitch 78 does not close immediately.

It will be readily appreciated that any suitable time delay switchingapparatus may be utilized in the system to provide the function ofinsuring a delay between the filling cycle and the ejection cycle. Ithas been found that a thermoelectric switching device such as has beendescribed is entirely [adaquate] adequate for the purpose.

It is of particular importance to point out that the safety means forpreventing the apparatus from remaining in the filling cycle onlybecomes operative upon the situation of improper functioning of thenormal means for shifting valve 22 from its normal to its alternateposition and back again, Normally, switch 62 will not be in positionwith pole 64 engaging contact 68 at the same time that pole 50 isengaging contact 52 of switch 48. Inasmuch as switches 70 and 62 operatetogether, the holding circuit for coil 46 is broken at the same timepole 64 of switch 62 is caused to engage contact 68. This permits switch48 to open simultaneously with the closing of switch 62 to prevent suchenergization of component 76. It is only when contact is made betweenelectrode 28 and ground, which continues the energizing of coil 46 whentimer 36 shifts its switches, that element 40 is operated.

The material-handling apparatus of this invention is particularly usefulfor the purpose of. handling sewage or the like which is to bedischarged against forces such as gravity. If it is desirable to employthe apparatus for such purposes, it is but necessary to install vessel10, and the control heretofore described operates automatically to ejectthe material through the force of air pressure or the like when apredetermined amount has been accumulated. There is no danger, becauseof the particular safety means, of the apparatus being ineffective forthe purpose of receiving material simply because the elec trode 28 forsensing the desired accumulation fails to function through fouling orthe like. When this occurs, the safety means automatically takes over toprovide a predetermined time delay between ejecting cycles of theapparatus, which delay may be preset to provide for the desiredaccumulation of material in vessel 10.

By utilizing rectifier 42 to change the alternating current from thesource of electrical energy into direct current before the energyreaches coil 46, it is possible to utilize a more sensitive electricalswitching device 34 to initiate the operation of the control system uponthe filling of vessel with material. Additionally, the direct currentflowing through electrode 28 in the energizing of coil 26 materiallyincreases the length of life of the electrode 28 over what would bepossible if alternating current were used in this energizing circuit.However, in order to provide for the use of half wave rectified currentwhich emanates from the source and the rectifier, capacitor 44 isinterposed between lines 110 and 112. Thus the direct current stored inthe capacitor 44 during the conducting half cycle of rectifier 42 isdischarged to energize solenoid 46 during the nonconducting half cycle.

Although the apparatus has particular application in the handling ofsewage, there is no intention to restrict its utilization for suchpurposes. On the contrary, this apparatus may be used for a wide rangeof functions.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. Material handling apparatus which comprises a closed materialreceiving vessel; inlet means connected to said vessel and adapted to becoupled to a source of material to be handled so as to permit the flowof material only in the direction of said vessel; vent means connectedto said vessel; conduit means connected to said vessel and adapted to becoupled to a source of fluid under pressure; valve means operablyassociated with said vent means and conduit means of said vessel, saidvalve means having a normal position that permits communication betweensaid vessel and said vent means and precludes communication with saidconduit means, said valve means being shiftable to an alternate positionwherein communication is established between said vessel and saidconduit means and wherein communication with said vent means isprecluded; means connected to said valve means for effecting theselective shifting of said valve means to the alternate position whensaid means is actuated; sensing means disposed within said vessel so asto be contacted by the material therein when a preselected level ofmaterial accumulation has been reached; outlet means connected to saidvessel so as to permit the flow of material therefrom; circuit meanselectrically connected to said valve shifting means so that said valveshifting means is actuated in response to the energization of saidcircuit means, said circuit means being energized in response to saidaccumulated material contacting and grounding said sensing means andbeing maintained in an energized state when said sensing means continuesto be grounded due to the fouling thereof; a first timing circuitelectrically connected to said circuit means, said first timing circuitbeing actuated a preselected period of time after the energization ofsaid circuit means, said preselected period of time corresponding to theperiod required to effect the discharge of a substantial portion ofaccumulated material from said material receiving vessel; said actuatedfirst timing circuit effecting the deactuation of said valve shift ingmeans to thereby return said valve means to the normal position andnormally effecting the dcenergization of said circuit means; and asecond timing circuit being alternately rendered effective andineffective for preselected periods of time as long as said sensingmeans continues to be grounded and in response to the continuedenergization of said circuit means whereby said valve shifting means isalternately actuated and deactuated for corresponding periods of timeand the material handling apparatus is alternated between a materialreceiving state and a material ejecting state.

2. In combination with material handling apparatus having a closedmaterial receiving vessel, including a vent communicating with thesurrounding environment and a supply conduit coupled to a source offluid under pressure, a selectively operable valve means that has anormal position which establishes communication between the vessel andthe associated vent and an alternate position that establishescommunication between the vessel and the source of fluid through theassociated supply conduit, an inlet means that permits the flow ofmaterial to the vessel and outlet means that permits the flow ofmaterial out of the vessel after a preselected level of materialaccumulation has been reached as indicated by the material contacting asingle probe sensing means that is disposed within the vessel; a controlcircuit which comprises means operably connectable to the valve means ofthe vessel so as to effect the shifting of said valve means when saidmeans is in an actuated state: circuit means electrically connected tosaid valve shifting means so that said valve shifting means is actuatedin response to the energization of said circuit means, said circuitmeans being energized in response to the accumulated material contactingand grounding said single probe sensing means and being maintained in anenergized state when said sensing means continues to be grounded due tothe fouling thereof; a first timing circuit electrically connected tosaid circuit means, said first timing circuit being actuated apreselected period of time after the cncrgization of said circuit means,said preselected period of time corresponding to the period required toeffect the discharge of a substantial portion of accumulated materialfrom said material receiving vessel; said actuated first timing circuiteffecting the deactuation of said valve shifting means to thereby returnsaid valve means to the normal position and normally effecting thedeenergization of said circuit means; and a second timing circuit beingalternately rendercd effective and ineffective for preselected periodsof time as long as said sensing means continues to be grounded and inresponse to the continued energiztation of said circuit means wherebysaid valve shifting means is alternately actuated and deactuated forcorresponding periods of time and the material handling apparatus isalternated between a material receiving state and a material ejectingstate.

3. Material handling apparatus which comprises a closed materialreceiving vessel; inlet means connected to said vessel and adapted to becoupled to a source of material to be handled so as to permit the flowof material only in the direction of said vessel; vent means connectedto said vessel; conduit means connected to said vessel and adapted to becoupled to a source of fluid under pressure; valve means operablyassociated with said vent means and conduit means of said vessel, saidvalve means having a normal position that permits communication betweensaid vessel and said vent means and precludes communication with saidconduit means, said valve means being shiftable to an alternate positionwherein communication is established between said vessel and saidconduit means and wherein communication with said vent means isprecluded; a solenoid connected to said valve means for eflecting theselective shifting of said valve means when said solenoid is actuated;single probe sensing means disposed within said vessel so as to becontacted by the material therein when a preselected level of materialaccumulation has been reached; outlet means connected to said vessel soas to permit the flow of material therefrom; circuit means electricallyconnected to said valve shifting solenoid so that said solenoid means isactuated in response to the energization of said circuit means, saidcircuit means being energized in response to said accumulated materialcontacting and grounding said single probe sensing means and beingmaintained in an energized state when said sensing means continues to begrounded due to the fouling thereof; a first timing circuit electricallyconnected to said circuit means, said first timing circuit beingactuated a preselected period of time after the energization of saidcircuit means, said preselected period of time corresponding to theperiod required to effect the discharge of a substantial portion ofaccumulated material from said material receiving vessel; said actuatedfirst timing circuit effecting the deactuation of said valve shiftingsolenoid to thereby return said solenoid to the normal position andnormally etfecting the deenergization of said circuit means; and asecond timing circuit being alternately rendered effective andinetfective for preselected periods of time as long as said single probesensing means continues to be grounded and in response to the continuedenergizetion of said circuit means whereby said solenoid is alternatelyactuated and deactuated for corresponding periods of time and thematerial handling apparatus is al ternated between a material receivingstate and a material ejecting state.

4. A circuit for controlling material handling apparatus including aclosed material receiving vessel that has a vent communicating with thesurrounding environment and a supply conduit coupled to a source offluid under pressure, the apparatus also having a selectively operablevalve means that has a normal position which establishes communicationbetween the vessel and the associated vent and an alternate positionthat establishes communication between the vessel and the source offluid through the associated supply conduit, the apparatus furtherincluding inlet means that permits the flow of material to the vesseland outlet means that permits the flow of material out of the vesselafter a preselected level of material accumulation has been reached asindicated by the matcrial contacting and grounding a single probesensing means that is disposed within the vessel; which control circuitcomprises means operably connectable to the valve means of the vessel soas to effect the shifting of said valve means when said means is in anactuated state; circuit means electrically connected to said valveshifting means so that said valve shifting means is actuated in responseto the energization of said circuit means, said circuit means beingenergized in response to the accumulated material contacting andgrounding said single probe sensing means and being maintained in anenergized state when said sensing means continues to be grounded due tothe fouling thereof; a first timing circuit electrically connected tosaid circuit means, said first timing circuit being actuated apreselected period of time after the energization of said circuit means,said presclected period of time corresponding to the period required toeffect the discharge of a substantial portion of accumulated materialfrom said material receiving vessel; said actuated first timing circuitel'lecting the deactuation of said valve shifting means to therebyreturn said valve shifting means to the normal position and normallyeffecting the deenergization of said circuit means; and a second timingcircuit being alternately rendered eiTective and inetiective forpreselected periods of time as long as said single probe sensing meanscontinues to be grounded and in response to the continued energizationof said circuit means whereby said valve shifting means is alternatelyactuated and deactuated for corresponding periods of time and thematerial handling apparatus is alternated between a material receivingstate and a material ejecting state.

5. Material handling apparatus which comprises a closed materialreceiving vessel; inlet means connected to said vessel and adapted to becoupled to a source of material to be handled so as to permit the flowof material only in the direction of said vessel; vent means connectedto said vessel; conduit means connected to said vessel and adapted to becoupled to a source of fluid under pressure; valve means operablyassociated with said vent means and conduit means of said vessel, saidvalve means having a normal position that permits communication betweensaid vessel and said vent means and precludes communication with saidconduit means, said valve means being shiftable to an alternate positionwherein communication is established between said vessel and saidconduit means and wherein communication with said vent means isprecluded; means connected to said valve means for effecting theselective shifting of said valve means to the alternate position whensaid means is actuated; sensing means disposed within said vessel so asto be contacted by the material therein when a preselected level ofmaterial accumulation has been reached; outlet means connected to saidvessel so as to permit the flow of material therefrom; circuit meanselectrically connected to said valve shifting means so that said valveshifting means is actuated in response to the energization of saidcircuit means, said circuit means being energized in response to saidaccumulated material contacting and grounding said sensing means andbeing maintained in an energized state when said sensing means continuesto be grounded due to the fouling thereof; a first timing circuitelectrically connected to said circuit means, said first timing circuitbeing actuated a preselected period of time after the cnergization ofsaid circuit means, said preselected period of time corresponding to theperiod required to efiect the discharge of a substautial portion ofaccumulated material from said material receiving vessel; said actuatedfirst timing circuit efl'ecting the deactuation of said valve shiftingmeans to thereby return said valve means to the normal position andnormally effecting the deenergization of said circuit means; and asecond timing circuit being initially energized a preselected period oftime after said first timing circuit and in response to the continuedenergization of said circuit means, said second timing circuit beingconnected in circuit with said circuit means so as to be alternatelyrendered effective and ineffective for preselected periods of time afterits initial energization so as to alternately actuate and deactuate saidvalve shifting means for corresponding periods of time.

6. A circuit for controlling material handling apparatus including aclosed material receiving vessel that has a vent communicating with thesurrounding environment and a supply conduit coupled to a source offluid under pressure, the apparatus also having a selectively operablevalve means that has a normal position which establishes communicationbetween the vessel and the associated vent and an alternate positionthat establishes communication between the vessel and the source offluid through the associated supply conduit, the apparatus furtherincluding inlet means that permits the flow of material to the vesseland outlet means that permits the flow of material out of the vesselafter a preselected level of material accumulation has been reached asindicated by the material contacting and grounding a single probesensing means that is disposed within the vessel; which control circuitcomprises means operably connectable to the valve means of the vessel soas to effect the shifting of said valve means when said means is in anactuated state; circuit means electrically connected to said valveshifting means so that said valve shifting means is actuated in responseto the energization of said circuit means, said circuit means beingenergized in response to the accumulated material contacting andgrounding said single probe sensing means and being maintained in anenergized state When said sensing means continues to be grounded due tothe fouling thereof; a first timing circuit electrically connected tosaid circuit means, said first timing circuit being actuated apreselected period of time after the energization of said circuit means,said preselected period of time corresponding to the period required toeffect the discharge of a substantial portion of accumulated materialfrom said material receiving vessel; said actuated first timing circuitelfecting the deactuation of said valve shifting means to thereby returnsaid valve shifting means to the normal position and normally etfectingthe deenergization of said circuit means; and a second timing circuitbeing initially energized a preselected period of time after said firsttiming circuit and in response to the continued energization of saidcircuit means, said second timing circuit being connected in circuitwith said circuit means so as to be alternately rendered effective andineffective for preselected periods of time after its initialenergization so as to alternately actuate and deactuate said valveshifting means for corresponding periods of time.

7. Sewage handling apparatus which comprises a sewage receiving vessel;means for supplying sewage to the vessel so as to effect theaccumulation of sewage therein; means for discharging accumulated sewagefrom the vessel; and means for controlling said discharging means; saidcontrolling means including sensing means disposed within sdid vessel soas to be contacted and grounded by said sewage when said sewage reachesa preselected level within said vessel, means responsive to theaccumulated sewage grounding said sensing means for actuating saiddischarging means for a predetermined period of time so that sewagewithin said vessel is discharged during said period of time; and meansresponsive to the fouling and continued grounding of said sensing meansfor alternately actuating and deactuating the discharging means forpreselected periods of time so that the vessel is alternatelyconditioned to receive sewage for a preselected period of time and todischarge sewage for a preselected 10 period of time notwithstanding thefouling and continued grounding of said sensing means.

8. Sewage handling apparatus which comprises a sewage receiving vessel;means for supplying sewage to the vessel so as to efiect theaccumulation of sewage therein; means for discharging sewage from thevessel; and means for controlling said discharging means; saidcontrolling means including sensing means disposed within said vessel soas to be contacted and grounded by said sewage when said sewage reachesa preselected level within said vessel, means responsive to theaccumulated sewage grounding said sensing means for efiecting adischarging cycle whereby a substantial portion of the accumulatedmaterial is discharged from said vessel, the normal condition of saidvessel being such as to receive sewage and precluding the discharge ofsewage therefrom, and means responsive to the fouling and continuedgrounding of said sensing means for automatically effecting alternateaccumulating and discharging cycles as long as said sensing meanscontinues to be .fouled and grounded.

9. Sewage handling apparatus which comprises a closed sewage receivingvessel; inlet means connected to said vessel so as to permit the flow ofsewage thereto; vent means connected to said vessel; conduit meansconnected to said vessel and adapted to be coupled to a source of fluidunder pressure; valve means operably associated with said vent means andconduit means of said vessel, said valve means having a normal positionthat permits communication between said vessel and said vent means andprecludes communication with said conduit means, said valve means beingshiftable to an alternate position wherein communication is establishedbetween said vessel and said conduit means and wherein communicationwith said vent means is precluded; means connected to said valve meansfor effecting the selective shifting of said valve means to thealternate position when said means is actuated; sensing means disposedwithin said vessel so as to be contacted by the sewage therein when apreselected level of sewage accumulation has been reached; outlet meansconnected to said vessel so as to permit the flow of sewage therefrom;first circuit means electrically connected to said valve shifting meansso that said valve shifting means is actuated by the energization ofsaid circuit means in response to accumulated sewage contacting andgrounding said sensing means, said first circuit means being deenergizeda preselected period of time after the energizazion thereof and normallyafter the ungrounding of said sensing means so that said valve shiftingmeans is deactuated, said preselected period of time corresponding tothe period required to eflect the discharge of a substantial portion ofaccumulated sewage from said vessel; and second circuit means beingalternately rendered effective and ineflective for preselected periodsof time as long as said sensing means is fouled and continues to begrounded whereby said valve shifting means is alternately actuated anddeactuated for corresponding periods of time and the sewage handlingapparatus is alternated between a sewage receiving state and a sewageejecting state notwithstanding the fouling of said sensing means.

10. A circuit for controlling sewage handling apparatus including aclosed sewage receiving vessel that has a vent communicating with thesurrounding environment and a supply conduit coupled to a source offluid under pressure, the apparatus also having a selectively operablevalve means that has a normal position which establishes cornmunicationbetween the vessel and the associated vent and an alternate positionthat establishes communication between the vessel and the source offluid through the associated supply conduit, the apparatus furtherincluding inlet means thut permits the flow of sewage to the vessel andoutlet means that permits the flow of sewage out of the vessel after apreselected level of sewage accumulation has been reached as indicatedby the sewage contacting and grounding a single probe sensing means thatis disposed within the vessel, which control circuit comprises meansoperably connectable to the valve means of the vessel so as to eflectthe shifting of said valve means when said means is in an actuatedstate; first circuit means electrically connected to said valve shiftingmeans so that said valve shifting means is actuated in response to theenergization of said circuit means, said circuit means being energizedin response to said accumulated sewage contacting and grounding saidsensing means, said first circuit means being deenergized a preselectedperiod of time after the energization thereof and normally after theungrounding of said sensing means so that said valve shifting means isdeactuated; said preselected period of time corresponding to the periodrequired to effect the discharge of a substantial portion of accumulatedsewage from said vessel; and second circuit means being alternatelyrendered effective and inefiective for preselected periods of time aslong as said sensing means is fouled and continues to be groundedwhereby said valve shifting means is alternately actuated and deactuatedfor corresponding periods of time and the sewage handling apparatus isalternated between a sewage receiving state and a sewage ejecting statenotwithstanding the fouling of said sensing means.

References Cited by the Examiner The following references, cited by theExaminer, are of record in the patented file of this patent or theoriginal patent.

MARK NEWMAN, Primary Examiner.

W. J. KRAUSS, Assistant Examiner.

